# Flux-closure domains in high aspect ratio electroless-deposited CoNiB nanotubes

### Submission summary

 As Contributors: Olivier Fruchart Arxiv Link: https://arxiv.org/abs/1704.06614v2 (pdf) Date accepted: 2018-10-21 Date submitted: 2018-05-21 02:00 Submitted by: Fruchart, Olivier Submitted to: SciPost Physics Academic field: Physics Specialties: Condensed Matter Physics - Experiment Approach: Experimental

### Abstract

We report the imaging of magnetic domains in ferromagnetic CoNiB nanotubes with very long aspect ratio, fabricated by electroless plating. While axial magnetization is expected for long tubes made of soft magnetic materials, we evidence series of azimuthal domains. We tentatively explain these by the interplay of anisotropic strain and/or grain size, with magneto-elasticity and/or anisotropic interfacial magnetic anisotropy. This material could be interesting for dense data storage, as well as curvature-induced magnetic phenomena such as the non-reciprocity of spin-wave propagation.

### Ontology / Topics

See full Ontology or Topics database.

Published as SciPost Phys. 5, 038 (2018)

### Submission & Refereeing History

Submission 1704.06614v2 on 21 May 2018

## Reports on this Submission

### Anonymous Report 1 on 2018-8-3 (Invited Report)

• Cite as: Anonymous, Report on arXiv:1704.06614v2, delivered 2018-08-03, doi: 10.21468/SciPost.Report.548

### Strengths

1. complete study of magnetic nano tubes from the fabrication to magnetic imaging.
2. combination of two x-ray microscopy techniques and comparison to MOKE.

### Weaknesses

1. A comparison between simulations and experiments would give a more detailed insight into the domain and domain wall structure.
2. The domain wall structure is not shown.

### Report

The Authors describe the fabrication, characterization and magnetic study of ferromagnetic nanotubes. They introduce the material systems and the imaging techniques used. They present the results clearly and draw the correct conclusions.

### Requested changes

-

• validity: high
• significance: good
• originality: high
• clarity: high
• formatting: excellent
• grammar: excellent

### Author:  Olivier Fruchart  on 2018-08-23  [id 309]

(in reply to Report 1 on 2018-08-03)
Category:
In the present manuscript we wished to report on a new material, displaying spontaneously azimuthal magnetization. Comment 3, and partly comment 1, are directly relevant for this concern. We fill that this comment is addressed in the manuscript by the following statement (page 7): "it is difficult to extract quantitatively the direction of magnetization in this series, because of the exponential decay of photon intensity inside matter, uncertainties in the dichroic coefficient, and the existence of a background intensity in the image. We can only provide an estimate of the $H_\mathrm{K}$ from the field for which all contrast vanishes in the corresponding images". While we could always attempt to reproduce the experimental STXM contrast, we fear that the several sources of uncertainties would prevent us from gaining more information than the fact that magnetization is azimuthal.